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@ARTICLE{Sirtl:455142,
      author       = {Sirtl, Maximilian T. and Armer, Melina and Reb, Lennart K.
                      and Hooijer, Rik and Dörflinger, Patrick and Scheel, Manuel
                      A. and Tvingstedt, Kristofer and Rieder, Philipp and Glück,
                      Nadja and Pandit, Pallavi and Roth, Stephan V. and
                      Müller-Buschbaum, Peter and Dyakonov, Vladimir and Bein,
                      Thomas},
      title        = {{O}ptoelectronic {P}roperties of ${C}s_{2}{A}g{B}i{B}r_{6}$
                      {T}hin {F}ilms: {T}he {I}nfluence of {P}recursor
                      {S}toichiometry},
      journal      = {ACS applied energy materials},
      volume       = {3},
      number       = {12},
      issn         = {2574-0962},
      address      = {Washington, DC},
      publisher    = {ACS Publications},
      reportid     = {PUBDB-2021-00957},
      pages        = {11597 - 11609},
      year         = {2020},
      note         = {Waiting for fulltext},
      abstract     = {Lead-free double perovskites have recently attracted
                      growing attention as possible alternatives to lead-based
                      halide perovskites in photovoltaics and other optoelectronic
                      applications. The most prominent compound Cs$_2$AgBiBr$_6$,
                      however, presents issues such as a rather large and indirect
                      band gap, high exciton binding energies, and poor charge
                      carrier transport, especially in thin films. In order to
                      address some of these challenges, we systematically modified
                      the stoichiometry of the precursors used for the synthesis
                      of thin films toward a BiBr$_3$-deficient system. In
                      combination with a stoichiometric excess of AgBr, we
                      obtained highly oriented double perovskite thin films. These
                      modifications directly boost the lifetime of the charge
                      carriers up to 500 ns as observed by time-resolved
                      photoluminescence spectroscopy. Moreover, time-resolved
                      microwave conductivity studies revealed an increase of the
                      charge carrier mobility from 3.5 to around ∼5 cm$^2$/(V
                      s). Solar cells comprising the modified films as planar
                      active layers reached power conversion efficiency (PCE)
                      values up to 1.11\%, exceeding the stoichiometric reference
                      film (∼0.97\%), both on average and with champion cells.
                      The results in this work underline the importance of
                      controlling the nanomorphology of the bulk film. We
                      anticipate that control of precursor stoichiometry will also
                      offer a promising approach for enhancing the efficiency of
                      other perovskite photovoltaic absorber materials and thin
                      films.},
      cin          = {DOOR ; HAS-User / FS-PET-D},
      ddc          = {540},
      cid          = {I:(DE-H253)HAS-User-20120731 /
                      I:(DE-H253)FS-PET-D-20190712},
      pnm          = {6214 - Nanoscience and Materials for Information Technology
                      (POF3-621) / 6G3 - PETRA III (POF3-622)},
      pid          = {G:(DE-HGF)POF3-6214 / G:(DE-HGF)POF3-6G3},
      experiment   = {EXP:(DE-H253)P-P03-20150101},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000618839200012},
      doi          = {10.1021/acsaem.0c01308},
      url          = {https://bib-pubdb1.desy.de/record/455142},
}